Facebook continues to defend its advertising value in a white paper released by ComScore today.

This is the second in a series of white papers that look at social marketing, and it reports that brands should take advantage of the social network's reach, fan engagement, and viral marketing qualities. It counters a recent survey that dubbed Facebook "boring," claiming that users are tuning out the network.

Facebook's marketing value has been debated for some time, and this report comes a month after General Motors pulled its ads from the social network, saying they weren't effective enough. The white paper highlights other ways Facebook is used as a marketing tool.

Exposure to fans means more business. Over a four-week period, Facebook fans and their friends were at Starbucks 38 percent more than people who were exposed to social-media networking.

Similarly, exposure to fans leads to exposure to friends through likes and Facebook timeline posts. Fans of Target were found to be 19 percent more likely to buy at Target in a four-week period following exposure, and the friends of fans were almost more likely to buy at Target 27 percent more of the time.

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Andrew Lipsman, ComScore's vice president of industry analysis, said the numbers show how brands can use both display advertising and the social network's "word of mouth" advertising for exposure.

"While marketers understand the importance of a channel that now accounts for 1 in every 7 minutes spent online, many are challenged to quantify its effectiveness," Lipsman said in a press release. "The Power of Like research sheds new light on how brands are able to deliver earned and paid media at scale, amplify its effects from fans to friends of fans, and understand how exposure to these media can drive the desired consumer behaviors, including online and in-store purchase."